Aniline Blue, Manufacture

On partly saturating the melt with concentrated hydrochloric acid, the hydrochloride of triphenylrosaniline separates out almost in a state of chemical purity, while impurities remain dissolved in the concentrated solution of aniline in aniline hydrochloride. This latter is separated and saturated with dilute acid, and the precipitate is worked up for inferior blue. This method of purification has completely replaced the older proeess with alcohol. 

The hydrochloride forms brilliant bronzy crystals, soluble in alcohol with a reddish-violet colour [39]. 

This base forms bluish-violet salts [28, 38], 

The free base is colourless and easily soluble in alcohol [28, 37,38]. 

TheAy rocA/orifi c, C2oHi7N3(C6H.,)3HC1, is the technical product obtained first in the fractional precipitation of the blue melt with hydrochloric acid. In this state it forms brilliant green crystals, insoluble in water and sparingly soluble in hot alcohol. Aniline dissolves it somewhat more easily. The alcoholic solution has a pure blue colour. Some of this product is used as spirit-blue, but by far the greater quantity is used for the manufacture of soluble blues. Triphenylrosaniline salts dissolve in sulphuric acid with a brown colour. 

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The commercial dyestuff is the hydrochloride of rosanilinc the acetate, however, is also sometimes met with. The free base is also prepared for the manufacture of aniline blue. 

FIGURE 7. Manufacture of aniline blue by phenylation (arylation) of amino groups in aniline red (magenta, fuchsine), 1860s. Edelstein Collection... 

During the following years Ivan Levinstein built up a reputation for the manufacture of aniline, its salts (used in aniline black printing), and aniline dyes. The failure of his brother Hugo to secure a process for the aniline blue when sued in a case of patent infringement in 1865 led Ivan to consider new patent-free processes and starting materials for preparing dyes, notably the use of toluene... 

Amino-5-nitro-2,l-benzisothiazole is manufactured by thiolysis of 2-amino-5-nitrobenzonitrile and oxidative ring closure. With aniline coupling components, shades from navy to greenish blue are obtainable (e.g., 28 and 29). 

In the industrial manufacture of acid azo dyes usually aniline derivatives are used as the diazo components. The coupling components for orange to blue shades are commonly aniline, naphthol, naphthylamine and aminonaphthol derivatives, whereas phenylpyrazolones are much used for preparing dyes in the yellow and orange shades. 

These bases are at present prepared by aniline-works in a state of great purity for instance the aniline employed in the manufacture of blue ( blue oil") is required to be chemically pure. 

The amount of aniline used in the manufacture of blue is of great importance. In presence of a large excess of aniline the phenylation is more complete and rapid than when a small quantity is used. For production of pure triphenylrosaniline (green shade of blue) a large excess of aniline is used (ten times the theoretical amount) along with a correspondingly large amount of... 

The azo compounds are important chromophores because of extended electronic delocalisation between the two aromatic rings via the azo bond. The darkness of the dye is enhanced by extensive delocalisation combined with several sulfonic acid groups which function as auxochromes. An example is provided by Naphthol Blue Black B (10), prepared from 8-amino-l-hydroxynaphthalene-3,6-disulfonic acid (H-acid) (11) by coupling it in the 7-position with diazotised p-nitroaniline in acidic solution and subsequently coupling in the 2-position with diazotised aniline in alkaline solution (Scheme 3). The H-acid (11) is a very versatile component in dye manufacture because it can couple with diazonium salts in either the 2-position or 7-position depending on the pH of the reaction medium, as indicated in Scheme 3. 

The iV-subsii lined anilines, available since the mid-1860s, became important intermediates in the manufacture of both the new triarylmethane and the azo colorants. /v,/v-Dimethylanilinc (32) was used by Caro to synthesize the thiazine dye methylene blue (33), the first colorant for which a patent was granted under the new German patent law (Scheme 11). In 1877, Otto Fischer achieved the synthesis from benzaldehyde and 32... 

AI3-03053 Aminobenzene Amlnophen Anilln Anilina Aniline Aniline oil Anyvim Arylamine Benzenamine Benzene, amino Benzidam Blue Oil C.l. 76000 C.l. Oxidation Base 1 Casweil No. 0510 CCRIS 44 Cl 76000 Cl Oxidation Base 1 Cyanol EINECS 200-539-3 ERA Resticide Chemical Code 251400 HSDB 43 Huile d anillne Krystallin Kyanol NCI-C03736 Rhenylamine RCRA waste number U012 UN 1547. Isolated from coal tar. Used as an intermediate in the manufacture of dyestuffs and pharmaceuticals. Oil mp = -6° bp = 184° d = 1.0220 soluble in H2O (3 g/100 ml), more soluble in organic solvents LDso (rat orl) = 0.44 g/kg. Lancaster Synthesis Co. Matlinckrodt Inc. Sigma-Aldrich Fine Chem. 

Nitrobenzene Used in the manufacture of aniline dyes and explosives also in the manufacture of perfumes, liqueurs and confectionery Greenish-blue discoloration of the mucous membranes, bluish-black line on the gums ... 

Synonyms 4-(phenylazo)benzenamine C.I. Solvent Yellow 1 p-aminodiphenylimide Solvent Yellow 1 Aniline yellow C.I. 11000 p-(Phenylazo)aniline 4-amino-i,i -azobenzene p-aminoazobenzol 4-benzeneazoaniline paraphenolazo aniline p-phenylazopheny-lamine AAB aminoazobenzene Brasilazina Oil Yellow G Cellitazol R Ceres Yellow R C.I. Solvent Blue 7 fast Spirit Yellow fast Spirit Yellow AAB fat yellow AAB induline r oil-soluble Aniline Yellow oil yellow AAB Oil Yellow AN Oil Yellow B Oil Yellow R Organol Yellow Organol Yellow 2A Somalia Yellow 2G Stearix Brown 4R Sudan Yellow R Sudan Yellow RA 4-(phenylazo)-benzamine Uses as a dye for lacquer, varnish, wax products, oil stains and styrene resins in insecticides used as an intermediate in the manufacture of Acid Yellow, diazo dyes and indulines Cross para groups of compounds A... 

Like Caro, Ivan Levinstein was educated at the Gewerbeinstitut in Berlin. There, Ivan studied the new aniline dyes, especially aniline red (fuchsine or magenta). In the early 1860s Levinstein Senior set up a factory in Berlin for the manufacture of synthetic dyes and in which the teenaged Ivan appears to have played a role. In 1864, however, Ivan Levinstein arrived in Salford, next to Manchester, and was soon preparing magenta on a small scale. By this time, blue and violet derivatives of magenta were available. 

Aniline, originally derived from coal tar, spawned the synthetic dye industry in the nineteenth century it is stUl used in the manufacture of dyes such as indigo (used in blue jeans), as well as in the manufacture of polyurethane, pharmaceuticals, and other chemicals. Consider the aqueous reaction shown in Table 1.1 between aniline and anilinium ion ... 

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